Objective To investigate the clinical application and effecacy of ulnar-sided thumb ladder progressive flap in repairing grade Ⅰ and Ⅱ thumb oblique wound.Methods Between October 2009 and October 2013,ulnar-sided thumb ladder progressive flap with double blood supply was transferred to cover the grade Ⅰ and Ⅱ thumb oblique wound in 24 patients (12 males and 12 females).Mean age was 30 years (range,10-40 years).Mechanism of injury was machine twist injury in 8 patients,machine cutting injury in 6,sharp weapon injury in 6 and injury by a heavy object in 4.Twelve patients had grade Ⅰ defect and twelve patients grade Ⅱ defect.Flap ranged in size from 1.0 cm ×3.0 cm to 1.5 cm × 3.5 cm.Flap advancement distance was 1.5-2.5 cm.Donor area was sutured directly.Wound healing and color,swelling and temperature of the flap were observed after operation.Finger function was assessed with the upper limb function evaluation standard set up by hand surgery branch of Chinese Medical Association.Results Postoperatively,the flap survived and the fingertip had protective sensation.The wound healed by first intention.Two patients developed distal interphalangeal joint stiffness,and restored to normal after rehabilitation.All patients were followed up for 1-36 months (mean,20 months).Finger color,temperature,texture and pulp were restored.Finger function recovered satisfactorily,with excellent results in 22 patients and good results in 2 patients.Conclusion The procedure is easy and reliable,has affirmative effect and achieves maximal preservation of finger length and function.